1. Field of the Invention
The present invention relates to a method of manufacturing a liquid droplet ejection head including nozzles that ejects droplets of a liquid such as ink, pressure chambers that are communicated with the nozzles and filled with a liquid such as ink, a diaphragm that configures part of the pressure chambers, a pool chamber that pools the liquid supplied to the pressure chambers via flow paths, and piezoelectric elements that cause the diaphragms to be displaced. The present invention also relates to a liquid droplet ejection head manufactured by this method and to a liquid droplet ejection apparatus disposed with this liquid droplet ejection head.
2. Description of the Related Art
Conventionally, an inkjet recording apparatus (liquid droplet ejection apparatus) has been known which prints an image (including characters) and the like on a recording medium such as recording paper by selectively ejecting ink droplets from plural nozzles of an inkjet recording head (sometimes referred to below simply as a “recording head”) serving as an example of a liquid droplet ejection head. In this inkjet recording apparatus, the recording head is of a piezoelectric type or a thermal type.
For example, in the case of the piezoelectric format, as shown in FIGS. 15 and 16, a piezoelectric element (an actuator that converts electrical energy into mechanical energy) 206 is disposed on a pressure chamber 204, and ink 200 is supplied to the pressure chamber 204 from an ink tank via an ink pool chamber 202. The piezoelectric element 206 is elastically and concavely deformed so as to reduce the volume of the pressure chamber 204, pressurize the ink 200 in the pressure chamber 204, and cause the ink 200 to be ejected as an ink droplet 200A from a nozzle 208 that is communicated with the pressure chamber 204.
With respect to an inkjet recording head with this configuration, in recent years there has been the demand to make the inkjet recording head capable of high-resolution printing while keeping the inkjet recording head inexpensive and compact. In order to meet this demand, it becomes necessary to dispose the nozzles in a high density. However, with current recording heads, there has been a limit on disposing the nozzles 208 in a high density because the ink pool chamber 202 is disposed adjacent to the nozzles 208 (in between the nozzles 208), as shown in the drawings.
Also, drive ICs that apply a voltage to predetermined piezoelectric elements are disposed in the inkjet recording head. Conventionally, as shown in FIG. 17, the drive ICs have been mounted with a flexible printed circuit (FPC) 210. In other words, the drive ICs have been connected to the surfaces of metal electrodes on the surfaces of the piezoelectric elements 206 disposed on a diaphragm 214 by joining bumps 212 formed on the FPC 210 to the surfaces of the metal electrodes. Because the drive ICs (not shown) are mounted on the FPC 210, the drive ICs become electrically connected to the piezoelectric elements 206 at this stage.
There is also a method where electrode terminals on a mounting substrate on which the drive ICs are mounted are connected to electrode terminals disposed on the outer surface of the recording head by wire bonding (e.g., see Japanese Patent Application Laid-Open (JP-A) No. 2-301445). And there is a format where the drive ICs are joined and connected to the electrode terminals disposed on the outer surface of the recording head, and then the FPC is joined and connected to electrode terminals of pullout wirings disposed in the recording head (e.g., see JP-A No. 9-323414)
However, in both cases, because wirings with a fine pitch (e.g., a pitch equal to or less than 10 μm) cannot be formed, there has been the problem that when the nozzle density becomes high, the size of the mounting substrate and the FPC becomes large, the compactness of the recording head is inhibited, and the cost of the recording head increases. There has also been the problem that when the nozzle density becomes high, wirings having a desired resistance cannot be pulled around. In other words, there is a limit on increasing the density of the nozzles due to the restriction of the wiring density.